Powdery Mildew of Roses and Ornamentals

Oidium and Sphaerotheca species


A fungal disease that causes a fine white powdery coating on leaves and buds. The leaves may be left blackened as the powdery coating falls off. Stems may be infected in severe conditions especially near thorns. If young leaves are infected they may be distorted or have a wavy appearance. Plant growth is often reduced and buds may fail to open or may form distorted and discoloured flowers.

Species Affected:

Ornamentals, Roses.
Granada and Folklore Roses are particularly susceptible.


Favoured by hot, humid weather.
The disease survives in dormant buds and on fallen leaves.

Life Cycle:

Origin and History:



Management and Control:

Destroy infected leaves.
Apply fungicides.

Related and Similar Species:


(McMaugh, 1985)


Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.